Method and device for controlling the drive train of an electric vehicle

Abstract

A method for controlling an electric vehicle drivetrain having least two drive units with wheels located on opposite axles are driven by respective drive units, includes in a first operating mode, the ratio of the torques provided by the drive units in each case for a given torque requirement is set taking into account the efficiency applicable to each drive unit under the given operating conditions, and in a second operating mode, the ratio of the torques provided by the drive units in each case for a given torque requirement is set independently of the efficiency applicable to each drive unit under the given operating conditions.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention This invention relates generally to controlling the drive train of an electric vehicle.[0002]2. Description of the Prior Art[0003]To increase the range of an electric vehicle, it is particularly important for the drive train to work as efficiently as possible. In a conventional drive train, the traction or electric motor and the transmission are designed such that both the requirements for performance of the electric vehicle and the requirements for efficient energy utilization are fulfilled.[0004]Whereas the performance criteria, i.e. the criteria regarding performance of the drive train, in an exclusively electrically driven motor vehicle require high torque and power values, the typical drive cycle of an electric vehicle takes place in the low torque and low rotation speed range, since in typical urban drive cycles and homologation cycles, the electric motor is usually operated with a comparatively low power and torque pr...

AI Technical Summary

Benefits of technology

The control method described in this patent improves the efficiency of the electric vehicle's drive train, allowing for longer journeys or faster driving. Additionally, the design allows for more powerful performance when needed. These improvements result in a longer range for the electric vehicle and a reduction in battery capacity requirements, leading to more usage benefits and lower operating costs.

Problems solved by technology

In this low load range, however, a conventional electric motor has low efficiency.

However in these cases, the performance criteria are not fulfilled as these performance criteria require higher nominal values for torque and power.

Designing the electric motor to have the optimum operating or working point in the homologation cycle load path, therefore, leads to a lower starting torque at high engine speeds, which in turn has the consequence that the electric motor is no longer able to deliver sufficiently high torque on a hill start or in scenarios with high rotation speed.

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